1. Field of the Invention
This invention relates to a video tape recorder (VTR), and more particularly to a two-channel VTR which records a video signal separated into two channel components on a magnetic tape and then reproduces the recorded signal.
2. Description of the Prior Art
Conventional 2 channel VTRs widely used for broadcasting and record video signals on a magnetic tape via two pairs of rotary heads in such a manner that a frequency modulated (FM) luminance signal Y and an FM chrominance signnal C are recorded on separate tracks which are arranged alternately in the order of Y, C, Y, C, Y, C,--. The FM Chrominance signal is a signal which is obtained by time-base-compression-multiplexing two chrominance difference signals and frequency-modulating the multiplexed signal, or a signal which is obtained by frequency modulating two chrominance difference signals with different carrier frequencies and mixing the frequency-modulated signals (so-called frequency-division-multiplexed signal), or a signal which is obtained by frequency-modulating so-called line sequential chrominance difference signals which appear alternately at a cycle of one horizontal scanning period. These are shown in Japanese Laid-Open Patent Application (Kokai) Nos. 59-4279, 59-34785, 58-131885, 59-104886 and 59-104887. Each pair of heads are disposed so as to be 180.degree. apart from each other on a circumference of a rotary cylinder. Each head of one pair is disposed adjacent to one head of the other pair. A typical conventional 2 channel VTR is shown in "A 1/2 inch Metal-Cassette VTR System" by S. Matsuda et al., Technical Report of the Institute of Television Engineers of Japan, Vol. 9, No. 2 (May 1985), pp. 19-24.
Although the conventional 2 channel VTRs can provide high quality video signals, they have the following disadvantages.
The conventional 2 channel VTRs operate in only one fixed operation mode, i.e., standard mode, but cannot operate in special operation modes such as a long play mode. If they were required to operate in an additional operation mode, two additional pairs of heads would have to be provided on the rotary cylinder, which would be very difficult or almost impossible.
Furthermore, the conventional 2 channel VTRs, when recording, provide a guard band between two adjacent signal tracks on the magnetic tape for eliminating crosstalk between the signals recorded on the adjacent signal tracks. This is disadvantageous with respect to increasing recording density.
Furthermore, since two heads are disposed adjacent to each other, production and adjustment of the head system is very difficult, and a shield plate must be provided between two adjacent heads for eliminating crosstalk between the two adjacent heads. As the result, the head system of the conventional 2 channel VTRs is too expensive for home use. This is the main reason for that the 2 channel VTRs have been used only for broadcasting.